1. Field of the Invention
The present invention relates to a method for fabricating a triangular prismatic m-plane nitride semiconductor light-emitting diode.
2. Description of the Related Art
Recently, a nitride semiconductor light-emitting diode having a principal plane of an m-plane has been researched and developed actively to improve the light-emitting efficiency. This is because a nitride semiconductor light-emitting diode having a principal plane of an m-plane is free from piezoelectric field, which decreases light-emitting efficiency. Hereinafter, a nitride semiconductor light-emitting diode having a principal plane of an m-plane is referred to as “m-plane nitride semiconductor light-emitting diode”.
US Pre-Grant Patent Application Publication No, 2013/0126902A discloses an m-plane nitride semiconductor light-emitting diode. As shown in FIG. 21, this m-plane nitride semiconductor light-emitting diode comprises an n-side electrode 30, an n-type nitride semiconductor layer 21, an active layer 22, a p-type nitride semiconductor layer 23, and a p-side electrode 40. A voltage is applied between the n-side electrode 30 and the p-side electrode 40 to emit light from the active layer 22.
According to the paragraphs [0161]-[0166] of US Pre-Grant Patent Application Publication No. 2013/0126902A, this m-plane nitride semiconductor light-emitting diode is fabricated as below. First, the n-type nitride semiconductor layer 21, the active layer 22, and the p-type nitride semiconductor layer 23 are epitaxially grown in this order on a substrate 10.
Then, a portion of the n-type nitride semiconductor layer 21, the active layer 22 and the p-type nitride semiconductor layer 23 is removed by dry etching using a chlorine-based gas to expose a part of the n-type nitride semiconductor layer 21. The p-side electrode 40 and the n-side electrode 30 are formed on the p-type nitride semiconductor layer 23 and the exposed part of the n-type nitride semiconductor layer 21, respectively.
Japanese Patent Application laid-open Publication No. 2012-023249A discloses a triangular prismatic m-plane nitride semiconductor light-emitting diode shown in FIG. 22. See FIG. 3G included in Japanese Patent Application laid-open Publication No. 2012-023249A. According to the paragraph [0199] of Japanese Patent Application laid-open Publication No. 2012-023249A, the lengths of the three sides of a triangle viewed in the top view of this triangular prismatic m-plane nitride semiconductor light-emitting diode are different from one another to improve light extraction efficiency.
Japanese Patent Application laid-open Publication No. 2009-071174A discloses a triangular prismatic m-plane nitride semiconductor light-emitting diode shown in FIG. 23. See FIG. 20 included in Japanese Patent Application laid-open Publication No. 2009-071174A. As shown in FIG. 23, the triangle viewed in the top view of the light-emitting diode disclosed in Japanese Patent Application laid-open Publication No. 2009-071174A is an isosceles right triangle. The longer side 1a of the isosceles right triangle is included in one cleavage surface selected from the group consisting of an a-plane and a c-plane.
Japanese Patent Application laid-open Publication No. Hei 11-340507A discloses a triangular prismatic c-plane nitride semiconductor light-emitting diode shown in FIG. 24. See FIG. 1 included in Japanese Patent Application laid-open Publication No. Hei 11-340507A. Note that the principal plane of the triangular prismatic nitride semiconductor light-emitting diode disclosed in Japanese Patent Application Laid-open Publication No. Hei 11-340507A is not an m-plane but a c-plane. A nitride semiconductor layer having a principal plane of a c-plane has cleavage surfaces of a (−1010) plane, a (01-10) plane, and a (1-100) plane. Japanese Patent Application laid-open Publication No. Hei 11-340507A discloses breaking a nitride semiconductor stacking structure having a principal plane of a c-plane along these three cleavage surfaces. In this way, provided is a triangular prismatic c-plane nitride semiconductor light-emitting diode.